Apparatus for burning liquid fuel



J. H. M ILVAINE APPARATUS FOR BURNING LIQUID FUEL Filed July 23, 1925 3Sheets-Sheet l Jail. 3, 1928.

Jan. 3, 1928. 1,654,658

J. H. MCILVAINE APPARATUS FOR BURNING LIQUID FUEL Filed July 23, 19%5 3Sheets-Sheet 2 a Jan. 3, 1928. 1,654,658

J. H. MCILVAINE APPARATUS FOR BURNING LIQUID FUEL Filed July 23, 1925 3Sheets-Sheet 3 digs.

Patented Jan. 3, 1928.

UNITED STATES JOHN H. MOILVAINE, 61? LAKE FOREST, ILLINOIS.

APPARATUS FOR BURNING LIQUID FUEL.

Application filed July 23, 1925. Serial No. 45,448.

This invention relates in general to proportional mixers, and moreparticularly one designed for carbon burners, commonly known as oilburners; and While certain principles of my invention may be applied inthe burningof any and all grades of fuel, the embodiment disclosedherein is intended for oil fuel of not lower gravity than 30 Baum. Myinvention' may be used for either industrial or domestic heating, itspresent application being to a furnace such as is used for heating theaverage home.

One of the objects of my invention is to improve the construction andoperation of liquid fuel burners with the viewto economizing in fuelconsumption, cost of operation, and maintenance. This is accomplished bysecuring more efiicient combustion and by employing a simple and noveloperv broader aspect of my invention, however, the

flame may be either continuous or intermittent, either constant inamount, or variable. In the practical application of my invention and inits preferred embodiment oil and air are fed in proper proportions andin certain predetermined amounts by an electric motor connected to acentrifugal pump and a centrifugal fan through suitable pipes to acombustion chamber. In my co-pending applic-ation, Serial No. 67 9,467,filed December 8, 1928, I employ a variable speed motor for drivingthefuel pump and air fan and by varying the speed of the motor I varythe fuel feed. The present application is, howi ever, confined primarilyto the use of a constant speed motor for driving the fuel pump and airfan or blower and to the means whereby the fuel and air feeds are inproper roportions .to maintain a continuous eificient flame throughout awide range of heats as applied to practically any installation.

use with liquid fuel or hydro- Some of the conditions and circumstancesattending the use of the burner will better explain certain purposes andobjects of my invention. The burner must be able to run at a flamesufficientl low so that practically no heat is given 0 on unseasonablywarm days. The flame must be capable of rapid increase to give theproper amount of heat, in the event of a sudden drop of temperature,without blowing out. Also there must be a suificient number ofintermediate positions to properly control the house temperature. Theburner must have suflicient capacity to keep the house at the avera etemperature desired such, for example, as 0 F. with the lowest outdoortemperature; and a high efiiciency of combustion must be obtained at allloads. Moreover, outdoor variations. of temperature and wind must notinfluence. the amount of air supplied or the efficiency will be lowereddue toeither incomplete combustion or excess air. The burner should beadapted to manual control at the mae chine or remote control by means ofa suitable thermostat, preferably one having three or more contactpositions. Some of the advantages of the continuous variable flame willbe readily recognized and appreciated. Inasmuch as the motor runscontinuously there is practically no need for the 'usual.

starting coils, switches, and auxiliary devices and mechanismsinvariably required for starting and stopping; consequently, the presentconstruction is free from man of the troubles followin from the use 0intermittently operate oil burners. High combustion efiiciency is alsoobtained y reason of the continuous flame. In the first place, at notime is any more heat being delivered into the heater or boiler than isnecessary, with resulting relatively low temperatures of the stack gasesat all loads, which means that the gases have given up more heat to theheater or boiler because they are never forced through faster thannecessary. Also there are no idle periods as obtained with anintermittent flame and as a result the efliciency is increased. This isevident when compared with an intermittently operating system in whichduring a considerable period of tlme after the flame starts, thecombustion chamber, boiler and plied for proper combustion; and, afterthe intermittent flame ceases, the boiler and fiues are very hot andcontinue to draw cold air through with resultant loss of heat. Anotherdecided objection to the latter type is that continually changing from amere pilot light to a very high heat and back again, sometimes manytimes a day, puts a great strain on the heater or boiler and fluesthrough rapid expansion and contraction, thereby causing cracks, leaksand displacements of the parts affected by the heat. The elimination ofthe gas pilot light or the electrical or combination ignition,absolutely prevents explosions through delayed ignition or blowing outof the pilot light when the gas pressure is low. Still another advantageof the present invention as compared with the prior intermittentlyoperating types of oil burners is that the number of mechanical parts isconsiderably reduced and the mechanism greatly simplified. It isbelieved that the present invention is a marked improvement over gravitytype burners,

especially in that more efiicient combustion is obtained throughpositive feed of air at all loads which is little affected by changes ofatmospheric conditions, as will be ex plained later.

In connection with the continuous flame type of burner I have aimedespecially to provide a simple and practical means for controlling andregulating the amounts of the air and fuel feeds. This control ischaracterized by its adjustment features whereby in its application topractically any heater or boiler it may be adjusted and setto deliversuchvolumes of air at the different loads as to produce eflicientcombustion at all times. This is very desirable since in practice thereare hardly any two heaters or boilers in which the conditions affectingcombustion are alike.

Other objects and attendant advantages will be appreciated by thoseskilled in this art as the invention becomes better under- .stood byreference to the following description when considered in connectionwith the I accompanying drawings, in whichlg. 3, is a similar viewlooking at the left hand side of Fig. 2;

Fig. 4 is an enlarged side elevation of the blower and air shuttercontrol;

as from a storagetank (not shown) to a service tank 11. From this tankthe oil flows by gravity through a shut-off valve 12, a strainer 13, andpipe 14 to a safety valve 15 adapted to shut off the flow to the burnerin case of any failure of the flame as will be discussed later. The oilthen flows through a pipe 15 to a float valve designated generally by 16mounted on a suitable frame 17 and serving to maintain the oil at aconstant level. From here the oil flows by gravity through a pipe 18 toa centrifugal pump 19 which is driven through a coiled spring connection21 by a constant speed electric motor 22. Both the pump and motor aremounted on the frame 17 in the operative relation shown. The pump 19 ispreferably of a special construction embodying the principles disclosedand claimed in my co-p'ending application, Serial No. 7 0,754, filedNovember 23, 1925. This pump has an oil inlet through the pipe 18 and anoutlet through the upstanding pipe 23, and a rotary impeller 24. Therevolving of the impeller raises the oil pressure to a head in theoutlet pipe 23 and in a standpipe 25, as for example, to the levelindicated by 26. Because the pump delivers a very small amount of oil ascompared to its full capacity with unrestricted flow, the churning ofthe impeller causes the formation of small air bubbles which, beinglighter than the oil, collect at the center of the impeller blade andtend to reduce the pressure of oil at the pump outlet. Provision is madefor allowing escape of this trapped air as explained'in my co-pendingapplication claiming this pump construction. The pump friction load onthe motor is practically eliminated by building the bearing for theimpeller shaft without a stuffing box, which allows a ver small amountof-oil t0 flow continuously a ong the shaft and out of the hearing at adrip point 27. The further course of this drip will be discussed later.The oil rises in the outlet pipe 23 by the action of the centrifugalpump and passes into the main standpipe 25 through a horizontal overflowpipe 28 which is higher than the level'of the oil in the float valve 16.Thus, when the motor stops, the pump also stops, the oil level drops inpipe 23 below the rises in the standpipe until it reaches theabove-mentioned point 26 above the overflow pipe 28, predetermined bythe diameter of the impeller, the speed of revolution of the motor andthe level of oil in the float valve. This arrangement of standpipe pipe29 and control valve 31 allows all the air, as far as the control valve,to escape through said standpipe, and likewise allows the escape of anybubbles of air' formed in the pump and thrown out by the impeller bladesinto the upstanding outlet pipe 23. The control valve governs the amountof oil fed to the burner and may consist of a globe type needle valvewith a threaded stem 32 on which an adjustment wheel 33 is mounted. onthis stem 32 is mounted for adjustable connection with the wheel 33, asby a set screw 30, a lever arm 34. through which the valve is connectedto an air control shutter which will be presently described. From thecontrol valve the oil flows through a pipe 35 which rises to an overflowdelivery point 36 from which point it drops through a vertical deliverypipe 37 having a sharp delivery point 38 from which the oil drops'intothe combustion-chamber designated generally by 39. The rise atthe'overflow delivery point 36v allows a steady flow of oil and preventsgushing. Also the pipe 35 rises gradually to said overflow deliverypoint to allow the escape of air beyond the control valve 31. Thepurpose of the sharp delivery point 38 is to allow the oil to drop offinto the combustion chamber 39 in a fine steady streanr even at a verylow rate without breaking up into large bubbles which would cause anintermittent and jerky flame with poor combustion resulting. In order toprevent premature vaporization of the oil in the oildeliverypipes theyare enclosed in the air delivery pipe 41 andalso in a verticallydisposed portion 42 in which the vertical delivery pipe 37 is heldcentered so as not to come in contact with the air-delivery pipe whichleads to the combustion chamber. The vertical oil-delivery pipe 37 .atits upper extremity may be vented by connecting through suitable pipesto theatmosphere at any suitable place, thus allowing the oil to flowfreely by-gravity from the overflow point 36 to the sharp delivery oint38 without any siphonic action; I pre er however, to have a lateralopening 43 facing into the column of air flowlng through .the airdelivery pipe 41, which arrangement assures a positive feed of oil downthrough the pipe 37 and also assists in breaking up the oil into smallparticles at the sharp delivery point 38, thus improving combustionespecially at high loads. The oil leaking out of the pump bearing at thepoint 27, as stated above, drops into a pipe 44 from the bottom of whicha small coiled copper tubing 45 leads to the main oil delivery pipeline. 35 beyond the control valve 31, from whence the drip oil flowswith the main oil supply to the combustion chamber. The small sizedtubing 45 functions as a damper and prevents sloshing back and forth ofthe body of oil between the level in pipe 44 and the overflow deliverypoint 36. The various parts of the apparatus are so arranged that thedrip point 27 is sufiiciently above the delivery point 36 to allow thepump leak oil .to go to that point by gravity even when the air pressurein the air delivery pipe 41 reaches its maximum. Note that the drippoint is about on a level with the armature shaft of the motor 22; thatis, at about the center of' theblower housing 48 (see Figs. 1 and 2).

The air delivery and control thereof is as follows The motor 22 has ashaft extension 46 on the end opposite from the oil pump 19 on which ismounted a centrifugal fan or blower wheel 47 which revolves in a blowerhousing 48 and which delivers air under low pressure to the air deliverypipe 41 leading to the combustion chamber 39. On the inlet side of theblower housing is mounted a plate 49. enclosing the blower wheel blades51 and having a central air inlet opening 52, The device for controllingthe an supply to' the blower, and consequently to the combustion'chamber, consists of a stationary shutter having a stationary part 53bolted to the intake side of the blower housing and a movable part 54mounted for rotative movement on a bolt 55 passing through and-supportedby the stationary part 53. A coiled compression spring 56 on the innerend of the bolt 55 acts through the latter movable shutter part 54seated against the stationary part 53 so as to prevent leakage of air tothe-blower inlet openin 52 through the contact surfaces of the two sutter parts. The stationary shutter part has two diametrically opposedopen quadrants 57 and 58 and intermediate closed quadrants 59 and 61.The movable shutter part comprises diametrically opposed closedquadrants 62 and 63 and intermediate open quadrants complemental to theopen quadrants 57 and 58 no t to hold the in thel'z stationary shutterpart. The open A quadrants in the movable shutter part are graduated insize, com' rising openings 64, 65 andiiltifl 68 and" 9-i'at'uthe oposits side and each is adapted to be close to a variable degree by aplate held in position on the shutter part '54, in this case byscrews71, said plates be ng a. t .,,one side 0 the shutter and 67,

numbered 72 to 77 inclusive. When the movable shutter part 54 is in theclosed position, that is, with ,the two quadrants containing theopenings 64 to 69 inclusive opposite the closed quadrants 59 and 61 ofthe stationary shutter part, no air may pass to the blower inlet opening52 through the shutter. In this position the blower fan wheel merelyrevolves in the housing and delivers no air to the combustion chamber 39except what reaches the blower housing through the opening for the fanwheel shaft and, in addition, through a series of small, low load inletholes 78 in the stationary shutter part 53 which may be plugged oropened to allow the proper amount of air to enter for supportingcombustion at low load. The amount of air admitted to the blower atdifferent successive positions of the movable shutter part may be variedby the position of the res ective plates 72 to 77 inclusive. This adustment is made when installing or setting up the apparatus for thepurpose of securing the desired amount of air in proportion to the fuelfeed at the different loads, as will be presently explained.

It is one of the purposes of my invention to connect the air and oilcontrols so that they are dependent one on the other for operation andwill consequently maintain a predetermined relative proportion betweenthe air and oil feeds. The connection between the movable shutter 54,which controls the air delivery, and the oil control valve 31 comprises,in this instance, a link 79 pivotally connected at one end 81 to -abracket arm 82 radially adjustable on the shutter part 5.4 by adjustmentof screws 83, and at its opposite end 84 to the lever arm 34abovementioned, on the stem 32 of the oil control valve. The lever armis adjustably connected to the stem 32, in this instance by a set screw30 which clamps againstthe periphery of a hand wheel 33 fixed to saidstem. The oil feed at low load is determined by setting the controlvalve 31 (by adjustment of the set screw 30) when the movable shutterpart 54 is in the closed position. By reason of the foregoingconstruction the air and oil feeds will be simultaneously opened andclosed in predetfimined relative rela-' tion so that the proportions ofthe oil and air will be correspondingly controlled. According to myinvention the air feed or delivery is variable at different loads tosuit the conditions peculiar to each installation, in some of whichgreater or less amounts of air may be required at the intermediate orhigher loads in proportion to the fuel feed, in order to assure completeand eliicient combustion at the different loads. This variable air feedis obtained by adjustment of the shutter parts for varying the size ofthe air inlet openings. It will now be observed that the-shutteropenings 64, 65 and 66 are located diametrically opposite from theplates 75, 76 and 77 .respectively, and that the openings 67, 68 and 69are similarly located with respect to the plates 72, 73 and 74. Thisarrangement is designed to permit adjusting the oil and air feeds atthis first position are,

however, accurately determined to suit the draftand other conditions athand, in the following manner: When the opening 64 is fully open and theopening 67 is just about to uncover part of the lower right openquadrant 58, a greater amount of air will be admitted through saidopening 54 than is necessary for supporting proper combustion of the oildelivered at this'position. The plate 72 will then he slid over part ofthe opening 64 to cut down the air supply to the correct amount and willthen be locked in such position by the screws 71. Similarly, a furthermovement of the shutter part 54 in the same direction will move the nextsucceednipulation of the wheel 33 on the oil control valve or the handle85 on the movable shutter part; or,,in the event that automatic controlis desired, a suitable thermostat regulator 86 is provided, in this casemounted on the frame 17 below the motor, blower,

etc., and connected to the movable shutter part by a link 87.

The combustion chamber per se and the method of burning the liquid fuelor hydrocarbon therefor, forms the subject matter of my companionapplication for Letters Patent, Serial No. 54,861, filed September 8,1925, but will be described herein in order to convey a clearunderstanding of the present invention. This combustion chamber isdesigned to fulfill the requirements of a continuous flame burner whichare discussed above, and its construction is an important factor to thepresent invention. The mixing or combustion chamber is, in its preferredembodiment, a casting, the shape of which is best shown in Figs. 7 8 and9. The vertical air-delivery pipe 42 fits into the inlet end shoulder 89of the combustion chamber casting which has an air inlet opening 91rectangular in cross-section. The combustion chamber is defined by avertical back wall 92, a vertical side wall 93 at right angles to theback wall; an opposed side wall which is curved in a vertical plane, asseen in- Fig. 9, and at an acute angle to the back wall in a horizontalplane, as seen in Fig. 7, a slanting bottom wall 95.making an acuteangle with the back wall 92, as seen in Fig. 8, a low load pocket-96extending out from the side wall 93 contiguous to the back wall, anoutlet opening 97 which is preferably circular as shown, and a top wallforming a hood over the outlet opening. The combustion chamber issupported inan upright position by suitable legs 98 integral with thecasting, which'rest on a base 99 which in turn rests on the furnacegrates 101 over which a layer of fire brick 102 is placed forprotection. The combustion chamber may, however, be supported in anysuitable manner in a furnace or heater according to the particularinstallation.

The operation is as follows: The blower and pump, driven at a constantspeed by the motor, w1ll deliver air and oil to the combustion chamber,as described above. The air and oil enter the interior of the combustionchamber through the opening 91. Oil drops by gravity from the deliverypoint 38 to the slanting bottom wall 95 and runs down to the lowestpoint of intersection of the bottom wall 95, back wall 92 and pocket 96,p or what I have termed the vaporizing. point 103. Wheninitiallystarting the burner it is necessary to preheat the combustionchamber as by means of a gas torch, gas flame, oil

soaked waste, or the l1ke for vaporizing and igniting the oil. After theburner is thus started the heat from the combustion of the oil willmaintain a temperature high enough to thereafter efl'ect vaporization ofthe oil and to produce a continuous flame, dependent of course, oncontinuous air and oil feed. The air jet coming thrcnlgh the inletopening 91 passes down along the side wall 93, impinges against theslanting bottom wall 95, V and mixes with the vapor at said vaporizingpoint 103. Here the mixture splits into two parts, the smaller of whichenters the pocket 96 where combustion begins with a spinning flame, thussupplying heat to the metal of the combustion chamber near saidvaporizing point. At low loads the burning mixture in the pocket 96constitutes a large percentage of the total combustion, in fact, thepocket functions as though it were a small auxiliary combustion chamberenabling a very low rate of oil consumption without the flame beingblown out or without the metal 1 becoming too cold for vaporization,thus making a separate form of gas or electric pilot light ignition, orother li hting means of this sort, unnecessary. T e flame in pocket 96emerges horizontally from the top half of the pocket and continues alongthat part of the back wall 92 at the rear of the pocket. This flamespins, as shown by the arrows, and joins the rest of the burning mixturealong the lower part of the back wall 92. As the amounts of oil and airare increased, the proportion of the burning mixture in pocket 96becomes less and less of the whole, but is always sufliciently largeenough to supply heat to the metal at the vaporizing point 103, at whichpoint at high loads a. small film of oil forms and spreads out along theintersection of back wall 92 with the bottom wall 95 and into the bottomof said pocket 96. Because the incoming air jet impinges'at an abruptangle to the surface of the oil film, the carbon residue is burned up asfast as it is formed. The main portion of the mixture at higher-loadsturns away from the pocket 96, along the bottom wall 95 and then upalong the curved side wall 94. The burning mixture is thus caused towhirl or revolve in the combustion cham: ber, as indicated by thearrows, but is held back in the chamber to some degree by the inclinedbottom wall 95 so as to prolon the vaporization period in the combustion0 amrevolving or whirling burning mixture inthe combustion chamber butat the same time allow it a smooth escape through the outlet opening 97which, it will be observed, is hooded at the top to throw the flame outhorizontally and to keep it as low as possible in the combustionchamberof the' furnace. The shape and proportions of the combustion chamber 39are such as to eliminate the formation of carbon deposit at any and allloads, to secure a thorough mixing of the fuel vapor and air, to g ve aclean white flame at all loads, and to reduce the noise usuall producedby the rapid combustion at big loads. The vertical mounting of thecombustion chamber gives a horizontal flame to touch the cold boilersurfaces (in a the boiler. In boilers where the fluesare opposite thecoal door, a fire brick baflle wall is placed a short distance in frontof the combustion chamber to deflect the hot. gases and throw them outat the side and top so that they will impinge on these surfaces of theboiler.

A pipe 10 1 leads from the base 99 to a trip bucket 105 which actuatesthe safety valve 15 above-mentioned. In case of any failure of theflame, oil fills in the combustion chamber 39, runs out into the base 99and partly fills the bucket 105 which then trips the valve 15, therebyshutting off the supply of oil to the furnace. The safety valve may alsobe actuated by overflow or leakage of oil into the drain pan 106 fromwhich the oil flows through pipe 107 to the bucket 105.

In use, in order to minimize the change of the chimney draft producedbychanges of outdoor conditions, the usual check draft door in the furnaceis opened to an amount equal in area to three or four times the area ofthe then becomes so high in comparison to the chimney draft that thechanges in outdoor atmospheric conditions have a negligible effect.

It is believed that the foregoing conveys a clear understanding of theobjects prefaced above and, While I have illustrated but a singleworking embodiment, it should be understood that many changes might bemade in details of construction and in the construction and arrangementof the several units and instrumentalities as may be required indifferent applications and for furnaces or heaters of different typesWithout, however, departing from the spirit and scope of the inventionas expressed in the appended claims, in whichclaim:

1. Fuel burning apparatus comprising, in combination, a combustionchamber, a blower for delivering air, means for delivering fuel to saidcombustion chamber, a control valve for regulating the feed of fueldelivered by said means, an air inlet control for the blower comprisinga plurality of separately adjustable shutter elements arranged to beadjusted one after another to secure a desired proportion of air to fuelat different loads, and means connecting said air inlet control and fuelfeed control to maintain a determined relation between the amounts ofair and fuel delivered to the combustion chamher at different loads.

' 2. Apparatus forburning gaseous or. vaporized 'fuel comprlsing, 1ncombination, a

bustion chamber, a control valve for regulating the feed of fueldelivered by said means, an air inlet control shutter for the blower,means connecting said shutter and and oil into the combustion chamber, acon trol valve for the oil delivery feed, a control valve for the airdelivery feed comprising a plurality of parts arranged for separateadjustment for different operating loads, and means connecting saidvalves to determine the relative proportions of air and oil delivered tothe combustion chamber at the diflerent loads, the parts of the aircontrol valve permitting independent adjustment of the air feed forevery step by step adjustment of the oil feed.

4:. Apparatus for burning liquid fuel comprising, in combination, acombustion chamber, a constant speed motor, an air blower and acentrifugal oil pump constantly driven by said motor and connected todeliver air and oil into the combustion chamber, a control valve for theoil delivery feed a control valve for the air delivery feed comprising ashutter plate, means connecting said valve and plate to determine therelative proportio-ns of air and liquid fuel delivered to the combustionchamber at the difierent loads, and means comprising a plurality ofseparately adjustable shutter pieces on said plate, each being arrangedto be set for a given operating load, for varying the amounts of airdelivered to the combustion chamber with respect to the amounts of oildelivered there-.

air under pressure to a combustion chamber 1 including a shutter controlfor the air operated in synchronism with the fuel feed control, saidshutter including variable openings for varying the amounts of airincrease with respect to the fuel increase at different loads. I

6. A fuel burning apparatus, means for feeding fuel, and mechanism fordelivering air under pressure to a combustion chamber including ashutter control for the air operated in synchronism with the fuel feedcontrol, said shutter having variable air openings. f i

7 .,A fuel burning apparatus for producing a constant flame variableto'high and low loads comprising, 'in combination, a combustion chamber,a constant speed motor, an air blower driven thereby and a fuel line fordelivering air and fuelto said combustion chamber, an air inlet shutterfor the blower comprising, in effect, a plurality of air valves and aplurality of air openings controlled thereby, each valve beingseparately adjustable to suit a particular operating load, a controlvalve for the fuel, and a control connection between said shutter andvalve for determining the proportions of air and fuel at the difierentoperating loads.

8. A fuel burning apparatus for producing a constant flame variable tohigh and low loads comprising, in combination, a combustion chamber, aconstant speed motor, an air blower driven thereby and a fuel line fordelivering air and fuel to said combustion chamber, an air inlet shutterfor the blower, a control valve for the fuel, and a control connectionbetween said shutter and valve for determining the proportions of airand fuel at the different operating loads, including means for aryingthe air delivery with relation to the fuel feed at said different loadswithout affecting the proportion of air to fuel at other loads.

9. Fuel burning apparatus comprising, in combination, a combustionchamber having fuel delivery means therefor, and means for deliveringair to said chamber including a blower for delivering air having ashutter comprising a stationary part and a movable part, the stationarypart having diametrically opposed air inlet quadrants and the movablepart having closed quadrants adapted to normally close said inletquadrants and also having a plurality of air inlet openings and meansfor varying the size of said openings, said air inlet open ings beingarranged to be moved in succes sion into registration with said airinlet quadrants by operation of the movable shutter part.

10. In a burner, in combination, a combustion chamber, and means fordeliverin fuel and air to said chamber in determined relativeproportions throughout the range of operation from low to high loadsincluding several separately adjustable means for varying the relativeproportions of air to fuel at low and high loads as well as at anyintermediate load, the said means permitting an independent adjustmentof the air p feed for every step by step adjustment of the fuel feed toinsure the proper proportioning of the two for all loads within therange of operation.

11. In an oil burner, in combination, a

combustion chamber, and means for delivering oil and air to said chamberin determined relative proportions throughout the range of operationfrom low to high loads including several separately adjustable means forindependently varying the relative proportions of air to oil at low andhigh loads as well as at any intermediate load, the said meanspermitting an independent adjustment of the air feed for every step bystep adjustment of the oil feed to insure the proper proportioning ofthe two for all loads Within the range of operation.

12. In a' fuel burning apparatus, in combination, a-combustion chamber,and means for delivering air to said chamber in regulated volumesincluding an air control shutter having plural series of airinletopenings and an adjustable closure for each opening, said openingsbeing arranged to open in succession, alternating from one series toanother.

18. In a fuel burning apparatus, in combination, a combustion chamber,means for delivering fuel and air to said chamber in-- cluding a fuelcontrol valve and a blower, the blower having an air inlet shutter, saidshutter having plural series of air inlet openings and an adjustableclosure for each opening, said openings being arranged to open insuccession, alternating from one series to the other, and means wherebythe fuel cont-rolevalve and air shutter will be operated to deliverdetermined proportions of fuel and air at various loads to thecombustion chamber.

14. In a fuel burning apparatus, in combination, a combustion chamber, avalve for furnishing fuel to the combustion chamber means for deliveringair to said chamber for supporting combustion including a blower havinga shutter for controlling the air inlet, means for admitting air to theblower when the shutter is in the closed position for supportingcombustion in said chamber when the fuel valve is in the low position,said shutter having plural series of air inlet openings and anadjustable closure for each opening, said openings being arranged toopen in succession, alternately from one series to the other.

15. In combination with a furnace, an air control including a shutterhaving a rela tively fixed and a movable part, the latter being adjustedfor proportioning the air supply with respect to the fuel supply, thefixed part being open for the admission of air, the movable partnormally closing the opening in the fixed part and having lural seriesof air inlet openings and an adjustable closure for each opening, saidopenings being arranged to be moved in succession over the opening inthe fixed part, the successive order alternating from one series to theother.

16. In combination, a combustion chamber, a valve controlled means fordelivering air to said chamber for supporting combustion, said air valvecomprising pivotally connected parts, one stationary and the otherrotatable, the. stationary part having diametrically opposed air inletquadrants and the rotatable part having diametrically opposed series ofair inlet openings and an ad1ustable' plate for each opening, said airinlet opemngs being so locatedaas to suecess vely uncover the quadrantopenings by I rotation of the movable part, the successive close to avariable degree its respective air nlet open ng so as to limit the airsupply 111 proportion to the fuel at different loads. 10

In witness of the foregoing I afiix my signature.

order alternating from one series to the other, and each plate beingadjustable to Patent No. 1, 654, 658.

JOHN H. MQILVAINE.

- CERTIFICATE OFYCORRECTION.

Granted January 3, 1928, to

JOHN H. McILVAINE.

It is hereby certified that error appears in the printed specificationofthe above numbered patent requiring correction as follows: Page 6, lines59 and 60,

claim 2, strike out "Apparatus for burning gaseous or vaporizing fuel"and insert "Fuel burning apparatus"; page 6, .lines 110 and 119, claims--5 and 6, strike out the article "A" and insert instead "In a"; andthat the said Letters Patent should be read with these correctionstherein'that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 31st dayof January; A. D. 1928.

M. J. Moore,

Seal. Acting Commissioner-of Patents.

mafia may wnform tn the 5. Moore, Jissismer @f Patents" lw l Signed andsealed this day of Januaay, A

Seal.

